Conventionally, as a write-once optical recording medium to and from which signals are recorded or reproduced by emitting light, for example, an optical disk recording medium (hereinafter, simply referred to as an optical disk) such as a Blu-ray Disc (BD, registered trademark) is widely used (for example, see Patent Document 1).
When data is recorded or reproduced with such an optical disk, there is a technique, which is called striping, for recording or reproducing in more than one channel. In striping, data is read from a plurality of different areas on the optical disk at the same time or data is recorded to those plurality areas at the same time.